When a color photographic silver halide light-sensitive material (hereinafter also sometimes referred to simply as a light-sensitive material) is exposed to light and then color-developed, an oxidized aromatic primary amine developing agent reacts with a dye-forming coupler to form a color image. In this method, color reproduction is usually achieved by the subtractive color process; that is, for reproduction of blue, green, and red, dyes of yellow, magenta, and cyan in complementary relation to blue, green, and red, respectively, are formed.
The couplers used in the above-described light-sensitive materials are dissolved in a high boiling point organic solvent or an alkaline aqueous solution and then dispersed in a photographic emulsion. In general, the former method, i.e., the oil droplet dispersion method, has an advantage of various excellent performances. Therefore, the couplers are required to be highly soluble in the high boiling organic solvents and excellent in dispersibility and stability in the photographic emulsion. In addition, it is demanded that the couplers show high color developing properties, such as maximum color density and dye-forming rate, and afford, upon development processing, a color image excellent in heat- and light-fastness, spectral absorption characteristics, and transparency.
Further, in view of the recent demand for minimizing environmental pollution, it is desired to use a color developer containing no benzyl alcohol while retaining the dye-forming properties of the couplers attained by using a color developer containing benzyl alcohol.
Such couplers that satisfy all of the above-described requirements have not yet been developed and an improvement has been long desired.
Phenols and naphthols are widely used as cyan dye-forming couplers. Conventional phenols and naphthols, however, have a disadvantage in that color images derived therefrom are inferior in storage stability. For example, color images derived from a 2-acylaminophenol cyan coupler described in U.S. Pat. Nos. 2,367,531, 3,369,929, 2,423,730 and 2,801,171 are generally inferior in heat-fastness. Color images derived from a 2,5-diacylaminophenol cyan coupler described in U.S. Pat. Nos. 2,772,162 and 2,895,826 are generally inferior in light-fastness. A 1-hydroxy-2-naphthamide cyan coupler can provide only color images which are generally inferior in both light-fastness and heat-fastness. Besides, these conventional couplers exhibit poor dye-forming properties in a color developer containing no benzyl alcohol.
The magenta dye-forming couplers include pyrazolone type compounds, pyrazolobenzimidazole type compounds, indazolone type compounds, pyrazolotriazole type compounds and pyrazoloimidazole type compounds. However, these couplers have various disadvantages. For example, a pyrazolone type magenta coupler disclosed in U.S. Pat. Nos. 2,369,489 and 2,600,788 has good dye-forming properties but shows insufficient dye-forming properties in a color developer containing no benzyl alcohol, and additionally the color density changes due to formalin, etc. The magenta couplers described in Japanese Patent Application (OPI) (Open to Public Inspection) No. 117034/74 are greatly dependent for dye-forming properties on the presence of benzyl alcohol, although some of them do provide color images excellent in light-fastness.
Compounds having an open-chain active methylene group are generally used as yellow dye-forming couplers. Conventionally known yellow couplers, e.g., those described in U.S. Pat. Nos. 3,408,194 and 3,644,498, provide color images having high light-fastness but their dye-forming properties greatly depend on benzyl alcohol. The couplers disclosed in Japanese Patent Application (OPI) No. 87650/75 exhibit stable dye-forming properties against pH changes of a color developer, but their dye-forming properties are greatly dependent on the presence of benzyl alcohol.